I'm very interested in hearing how the Dark Horse crank works for you.
I have been chasing a vibration issue with my 17 RK SP and just about ready to send it. LOL
I did the FM 124 big bore a over year and a half ago and currently have a little over 20k on the 124cc build. Up to recently it has been running terrific with no vibrations other than the normal Harley stuff. I had been focusing on suspension (RWD front and rear) and brakes (13" Galfer rotors with Brembo mono-blocks calipers off a 'Busa with the Speed Merchant adapter bracket) when this vibration started. I do ride it hard and tend to push it beyond what it was designed for, my back up ride is a '15 ZX14R, but I ride the Harley a lot more cause it's way more fun to give sport bikes and WRX's a hard time on my Harley, LOL
About 2 months ago it developed an abnormal, droning vibration. Feel it in the handlebars, floorboards and through the seat. It comes on in every gear at about 2000 rpm and only fades when above 4500 rpm. Its worse at around 75mph regardless if in 5th or 6th gear. If I pull the clutch in at 75-80 mph and coast the vibration for the most part goes away. If I still continue to hold in clutch, but bring rpm's up to 2500-3000 rpm, vibration returns. If I keep my knee on the air cleaner during this test, the engine itself feels normal, ie, I'm not feeling the vibration with the contact. It's a vibration that is very uncomfortable to the point that I wont ride it till it's fixed. Anything more than 15 minutes on the freeway and I'm done, hands and feet are achy and asleep, just pretty much not any fun.
I started with the basic stuff first, verified exhaust system installation, muffler bushings were worn, replaced but vibration still present.
I currently have a little over 40k miles overall on the bike so maybe it was time to replace the wheel bearings. Front and Rear bearings replaced, vibration still present.
Pulled the primary cover I don't know how many times now, Checked my clutch pak. I installed a Rekluse Torq Drive clutch kit last summer (not the auto clutch), maybe I put something together incorrectly. Everything checked out good, re-assembled, vibration still present.
Wel s#!*, maybe the compensator is taking a crap, ordered up a Man O War, pulled primary again, installed the new sprocket, vibration still there.
I was getting a subtle knock on the right floorboard occasionally, so maybe my motor mounts are done. Ordered up some Glide-Pro front and rear mounts. The front mounts were pretty worn, especially the front left, the 'washer' was separated from the bushing. The rears were un-remarkable, I was excited that I thought I may have found my issue. NOPE!
Pulled wheels and had the tires balance and mount rechecked. NOPE! Running the Metzler CruiseTec by the way. Awesome tire! very good grip and the 'turn in' is much more sport bike like than even the Pirelli Nite Dragons. My only issue with those is, I can only get about 6-7 k out of them before they are done.
Next stop, The Crank. Sounds like a movie title. Wait, wasn't there a movie............................................. ...........checked the cam side run out first, it was a little over .005. Pulled the primary, AGAIN, and ditto, a little over .005 on the PTO side. I spoke with Andrew at Dark Horse Crank works, he was very helpful by the way. He seemed to think that those numbers shouldn't be causing anything as bad as I'm feeling. Hell, the MOCO's recommended max run out is .012! Andrew verified primary chain condition, any 'tight spot' and sprocket/hub alignment with me. All this checked out. Sooooooooooooo
Currently, right now, I have the primary off, AGAIN. Waiting for some specialty tools to arrive so I can change out the inner primary bearing/race and also the clutch hub bearing. I've decided that since I'm here, I should pull the gear set out of the trans and verify that everything is satisfactory, as I have heard of some riders having issues with 3rd gear.
I did notice when dis-assembling the clutch that the inner clutch hub seemed to be off-center where the spline is pressed into the hub and does have a slight wobble that can be seen when mounted on the main-shaft. I thought that this could have been my source of vibration, but it sounds like from what I was able to find researching the internet, that this is normal. ??HUH?, I never noticed this before. Any one else know more regarding this?
Sorry for the long letter. I'm hoping maybe you or somebody else may have had a similar experience and could give me some insight.
I am interested in hearing more about your set up once you get some saddle time.
If this clutch hub wobble is 'normal' and I don't find any issues in the gear box along with replacing the aforementioned bearings, I'll probably be looking at doing the crank over the winter.
Approximately, what options did you choose for your crank? Did your builder send in your bottom end? or just the crank?
Thank you!
Here's a photo of my bike currently
Wow! Sounds like you’ve tried everything. I know the M8 cranks are a little stronger than the tc’s, but, you’re probably over it’s threshold. My runout on my cam side was .004 I have no idea what my sprocket side is, but, I’m starting to feel a slight vibration. Not going to chance it. Yours sounds bad, but, it’s even on both sides. I wonder if it’s just your left side bearings. I bought the Man-o-war crank, so, no need to send mine back. My Indy can and will do my left side bearings in his shop. My Man-O-War sprocket, became louder with the neutral knock. They’re replacing sprocket for free. They said mine was an older design, and the newest one is more forgiving. Don’t know exactly what that means. Also going to an S&S cam plate and oil pump. That wobble you spoke of, can’t be normal. You’ve got the best clutch kit made, I’m jealous of that. You can’t F’ it up, by replacing or trueing your crank. I chose the MOW because I wanted the best, and I wanted less downtime. What does your dyno-tune look like?
Also, and this may sound really stupid, check that your muffler mount, under the saddle bag, is lined up, and not touching the saddlebag support bracket. I had a real bad vibration once, and it turned out to be that. I know how ridiculous that sounds, but I seem to remember those exact symptoms.
Last edited by Bafflingbs; 10-16-2020 at 12:15 PM.
Hi, thanks for the reply.
I did go through and verified my exhaust system. The rear muffler bushings were worn out, so I replaced with new bushings. But, unfortunately, that didn't cure the vibration.
I did have the same experience with my Man O war sprocket as you. Sounded like they were tweaking the sprocket teeth design. I noticed on my sprocket, it didn't want to release the chain after going through it's rotation. I sent mine in and it quickly came back with an updated sprocket. I actually thought this was my vibration issue. But after a quick test ride, I found out that wasn't it.
My Dyno came out around 140/140. I'm unable to find my copy to post right now, have 120tq at 2600 and stays between 120- 140 all the way up to 5500 before it drops off.
I'm running Galfer 13' radial rotors purchased from IMZZ. I was told by Galfer they are thicker than non-radial rotors. I found a set of take-off 108mm Brembo calipers on E bay off a '15 Hayabusa ABS for $340.00. I used the Speed Merchant radial 13" caliper adapters purchased from Hard Case .
Everything lined up pretty good, diameter wise, didn't have to do any shimming for that.
Had to add about 4mm to center caliper laterally in relation to the rotor center line.
I'm currently using the stock master cylinder and stock brake lines. Even with the oem MC, braking now is 2 finger for aggressive riding and noticeably better than the original set-up. The big improvement I've noticed is the initial feel is much improved and lack of fade. I can have fun on the twisties and now I do not wonder if my brakes are toast for the next corner. Wave rotors do make more 'noise' whether on or off the brakes, I'm used to this from riding sport bikes.
I will update to a radial MC and change out brake lines by next summer, if I can figure out this vibration, lol.
I used the ITM-HD2 ABS brake bleed system mentioned in other threads on this forum to bleed the ABS system. Great product, easy to use.
Note: I did flip the right hand rotor around since that photo. It didn't look right to me visually. If you notice in that photo, the vent cuts weren't 'rolling' the correct direction during forward motion.
Hi, thanks for the reply.
I did go through and verified my exhaust system. The rear muffler bushings were worn out, so I replaced with new bushings. But, unfortunately, that didn't cure the vibration.
I did have the same experience with my Man O war sprocket as you. Sounded like they were tweaking the sprocket teeth design. I noticed on my sprocket, it didn't want to release the chain after going through it's rotation. I sent mine in and it quickly came back with an updated sprocket. I actually thought this was my vibration issue. But after a quick test ride, I found out that wasn't it.
My Dyno came out around 140/140. I'm unable to find my copy to post right now, have 120tq at 2600 and stays between 120- 140 all the way up to 5500 before it drops off.
Did the updated sprocket help with anything? Did you notice any difference? 140/140 sounds like a lot of fun!
Last edited by Bafflingbs; 10-17-2020 at 08:00 PM.
Added ohlins 772 (hd159 but black) and cut 2.5” out of the shifter and the brake. Thrashin floorboards set back. Trying to get my feet closer to mid controls. Might just go to mids but
don’t want to change my pipe right now.
shorter shifter is awesome, though harder to find neutral.
2.5” out of the brake is a little too much I think. I HATE the crazy angle of the stock setup. Covering the rear brake is very uncomfortable. This made it MUCH better but gave up a lot of leverage. I think splitting the difference will be comfortable and still function well. We will see.
anyway, some testing pics. And testing my new track suit lol
I working out a design that hopefully will be cheaper than the readily available mid kits on the market. I'll post it up once complete. maybe a month or so.
bike looks great and those boards look well and adjust nicely.
QUOTE=Puglia10;19476451]Added ohlins 772 (hd159 but black) and cut 2.5” out of the shifter and the brake. Thrashin floorboards set back. Trying to get my feet closer to mid controls. Might just go to mids but
don’t want to change my pipe right now.
shorter shifter is awesome, though harder to find neutral.
2.5” out of the brake is a little too much I think. I HATE the crazy angle of the stock setup. Covering the rear brake is very uncomfortable. This made it MUCH better but gave up a lot of leverage. I think splitting the difference will be comfortable and still function well. We will see.
anyway, some testing pics. And testing my new track suit lol
Did the updated sprocket help with anything? Did you notice any difference? 140/140 sounds like a lot of fun!
Unfortunately, the 'updated' sprocket from Dark Horse did not solve my vibration issue.
I am now going through and checking and replacing the bearings/seals as needed that are located on the clutch hub, main-shaft, inner primary, and transmission. I just pulled the gear-set today after finally getting the sprocket pulley nut removed. What a PIA!
Everything looks pretty good in the gear box except 5th gear input has some 'chatter' on it. Not sure what would've caused this. So probably will replace that too.
The needle bearings in the output shaft seem to be a little sloppy, so will replace those too. Everything else looks good in the transmission otherwise.
I am hoping that after all this, my vibration will be no longer. I haven't found anything real obvious yet.
10-16-2020, 12:00 PM
